1. Field of the Invention
The present invention is related to a display device, and more particularly, to a scan structure in a display device for decreasing a duty at a passive panel, a method for driving the display device, and a method for manufacturing the same.
2. Discussion of the Related Art
Recently, flat panel displays have been rapidly developed. In especial, the flat panel display such as a liquid crystal display (LCD) device substitutes for a cathode ray tube (CRT). Also, the flat panel displays such as a plasma display panel (PDP), a vacuum fluorescent display (VFD), a field emission display (FED), a light emitting diode (LED) and an electroluminescence (EL) are being actively researched.
The flat panel displays can be used in various fields in that the flat panel displays have an excellent visual perception, a high resolution and simplified process steps.
With a trend of large sized and high resolution flat panel displays, more current is used in a driving circuit for driving the displays, and for obtaining desired luminance in the displays.
In this respect, the LCD devices are generally used in monitors for portable information terminals due to less power consumption even though the LCD devices have disadvantages in a response time, a viewing angle and a color depth, as compared to other flat panel displays. However, considering a backlight of the LCD device, the LCD does not consume less power. Accordingly, a transflective or reflective type LCD device having no backlight is generally used.
Recently, with a tendency of the large sized flat panel displays, the organic EL display panel has attracted considerable attentions in that the organic EL display panel occupies small space.
The EL display panel obtaining thinness is addressed in a matrix type, and is driven at a voltage of 15 or less.
FIG. 1 is a view showing a structure of a related art passive driving type organic EL device.
As shown in FIG. 1, the device includes an organic EL panel 100, a data driver 2 and a scan driver 3. At this time, a data line 5 and a scan line 6 are formed in a matrix type on the organic EL panel 100 for emitting lights. Then, the data and scan drivers 2 and 3 apply currents to the data and scan lines 5 and 6, so that light is selectively emitted from the organic EL panel 100.
Process steps for manufacturing the organic EL panel 100 will be explained.
First, a transparent electrode is formed on a glass substrate. At this time, the transparent electrode is generally formed of indium tin oxide (ITO). However, the ITO has a high one resistance value, so that a supplemental metal electrode 4 is formed on the glass substrate before forming the transparent electrode or is formed on the transparent electrode.
Subsequently, a barrier 3 is formed for forming the scan line, and an organic material is deposited on entire surfaces of the organic EL panel 100. Then, the scan line is formed of metal, thereby completing the organic EL panel 100.
If a resolution of the organic EL panel 100 having the above structure is 128×128, a total duty is
      1    128    ,, which is in inverse proportion to the number of the scan lines.
If a frame frequency is 60 Hz, a scan time Ts assigned to each scan line is calculated as the following equation 1.
                              T          ⁢                                          ⁢          s                =                                            1              128                        ×                          1              60                                =                      130            ⁢                                                  ⁢            μ            ⁢                                                  ⁢            s                                              equation        ⁢                                  ⁢        1            
If the scan time Ts assigned to each scan line is increased, the power consumption is decreased, and it is possible to easily control luminance of each electrode.
As shown in FIG. 2, a method for physically decreasing a duty in half is used for increasing the scan time Ts.
FIG. 2 is a view showing an improved passive driving type organic EL according to the related art.
As shown in FIG. 2, the display panel (or EL panel 100) is divided into two parts, lower and upper parts, according to a direction of the scan line. That is, the display device is driven in a dual scan method.
The display panel, driven in the dual scan method and having the resolution of 128×128, includes first and second data drivers 2a and 2b for applying signals to 128 data lines 5, and a scan driver 1 for applying signals to 128 scan lines 6a and 6b divided into two parts, each part having 64 scan lines.
In the display panel 100 having the above structure, one scan signal is simultaneously applied to the scan line 6a of one part, and to the scan line 6b of the other part.
The scan signal applied to the signal line 6a of one part (upper part) is connected to the second data driver 2b, so that light is emitted from corresponding electrode. Also, the scan signal applied to the signal Line 6b of the other part (lower part) is connected to the first data driver 2a, so that light is emitted from corresponding electrode.
If the frame frequency is 60 Hz, the scan time assigned to each scan line is calculated as the following equation 2.
                              T          ⁢                                          ⁢          s                =                                            1              64                        ×                          1              60                                =                      260            ⁢                                                  ⁢            μ            ⁢                                                  ⁢            s                                              equation        ⁢                                  ⁢        2            
As explained above, the scan time assigned to each scan line is doubled, so that the duty is physically decreased in half, thereby decreasing power consumption.
However, the related art dual-scan structure of the display device and method for manufacturing the same has the following problems.
First, a plurality of data drivers is formed in the display device, so that a size of the device is increased, and the system is complicate.
Also, the display panel is divided into two parts, each part having the data driver for applying signals. Accordingly, a current difference may be generated between two parts, thereby deteriorating uniformity of image.